• KIEAE Journal
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• v.10 no.5
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• pp.151-157
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• 2010

This study is connected with evaluation of the progressive collapse resisting capacity for sustainable RC super tall building design. As the progressive collapse is not considered in current design codes in Korea, differences between linear static and dynamic analysis based on the GSA guidelines was analyzed for better evaluation, and the analysis model of flat plate system was determined. Finally, the progressive collapse resisting capacity was evaluated for structural system of super tall building. According to this study, the results by linear dynamic analysis were underestimated than the results by linear static analysis. Thus, the dynamic coefficient value of 2 provides conservative approach. The Effective Beam Width's model, currently used in field, is useful for the analysis about lateral force, but this model does not consider the effect of load redistribution by the slab. Hence, finite element analysis considering slab element will be needed for progressive collapse resisting capacity of the flat plate system. Finally, analysis model of 80-story building designed based on KBC(Korea Building Code) shows the weakness against progressive collapse because the DCR value is over 2. Thus, the countermeasure for alternative loading path such as installment of spandrel beam and reinforcements around slab is required to prevent the progressive collapse.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.8
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• pp.506-509
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• 2003

This paper describes the possibility of analyzing gait pattern from the changes of the lower leg electrical impedance. This impedance was measured by the four-electrode method. Two current electrodes were applied to the thigh, knee, and foot., and two potential electrodes were applied to the lateral, medial, and posterior position of human leg. The correlation coefficients of the joint angle and the impedance change from human leg movement was obtained using a electrogoniometer and 4ch impedance measurement system developed in this study. We found the optimal electrode position for knee and ankle joint movements based on high correlation coefficient, least interference, and maximum magnitude of impedance change. The correlation coefficients of the ankle, knee, and the hip movements were -0.913, 0.984 and 0.823, respectively. From such features of the human leg impedance, it has been made clear that different movement patterns exhibit different impedance patterns and impedance level. This system showed feasibility that lower leg movement could be easily measured by impedance measurement system with a few skin-electrodes.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.45-49
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• 2008

This paper investigated the accuracy of the current design formulae for the elastic buckling strength of web-tapered I-beams in AISC-LRFD specification. The basic concept is to replace a tapered beam by an equivalent prismatic beam with a different length, but with a cross section identical to that of the smaller end of the tapered beam. The modification factor, B, is used to account for the stress gradient within the unbraced length and the lateral restraining effects offered by the adjacent segments. The modification factor(B) suggested in AISC-LRFD specification was compared with the finite element method(FEM) results. This paper presented a redefined method to calculate the modification factor(B).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4185-4191
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• 2015

The demand for improved rail transportation safety is growing due to the increased speeds of current railways. In addition, freight trains with heavier axle loads are required to run on conventional railways. In order to meet these requirements, increased rail weights and the application of a CWR system have been introduced on conventional railways. The H type sleeper, which has higher lateral resistance than the existing mono sleepers, has been recently developed to increase track stiffness and reduce track irregularities. In this paper, the effects of a H-type sleeper on track behavior were investigated by 3-Dimensional F.E. analysis.

• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.115-123
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• 1998

In design of tall buildings, the flows of stress and ultimate strength of structures cannot be obtained by the elastic analysis alone. The current inelastic analysis are very impractical for practical engineer due to the amount of work involved in engineering calculation. In this paper the PC-based inelastic analysis by the residual strength ratio concepts is introduced. The efficiency of inelastic analysis is evaluated by comparing the results of inelastic analysis with those of elastic analysis for the existing tall buidling located in Seoul. Some modification in terms of lateral resisting structural system is proposed to improve the system ductility.

• Journal of fish pathology
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• v.21 no.2
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• pp.139-148
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• 2008

Vertebral deformity in hatchery-reared black sea bream (Acanthoparus schlegelii) fingerlings occurred. Deformed fish had a good appetite but no clinical signs were found except the vertebral abnormality and darkness around the dorsal skin of the deformed vertebra. As more than 90% of the hatchery-reared fish exhibited vertebral abnormality, the fingerlings could not be used for commercial seeds any more. No morphological change in the swim bladder was observed. Histopathological changes on the deformed vertebra, gill, liver, and spleen were observed to clarify the cause of the deformity. The vertebra were irregularly deformed upward with the shape of "V" in an alphabetic character causing the spinal cord and dorsal aorta suppressed. The diameters of the muscle fibers around the deformed vertebra, especially, in the dorsal part, were much smaller and more irregular than those in normal fish, and the gabs between the fiber bundles were enlarged. No evidence of inflammatory responses in the lateral musculature were found. On the basis of normal inflation of the swim bladder, cultural environments for growth of the fingerlings, and histopathological alterations in the muscle, vertebra and gills, it is suggested that high speed of water current in the culturing aquaria between 23 to 30 days after hatching was responsible for the development of vertebral abnormality.

• Earthquakes and Structures
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• v.18 no.6
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• pp.667-675
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• 2020

The current study compares the effect of structure-soil-structure interaction (SSSI) on the dynamic responses of adjacent buildings and isolated structures including soil-structure interaction (SSI) with the responses of fixed-base structures. Structural responses such as the relative acceleration, displacement, drift and shear force were considered under earthquake ground motion excitation. For this purpose, 5-, 10- and 15-story structures with 2-bay moment resisting frames resting on shallow foundations were modeled as a group of buildings in soft soil media. Viscous lateral boundaries and interface elements were applied to the soil model to simulate semi-infinite soil media, frictional contact and probable slip under seismic excitation. The direct method was employed for fully nonlinear time-history dynamic analysis in OpenSees using 3D finite element soil-structure models with different building positions. The results showed that the responses of the grouped structures were strongly influenced by the adjacent structures. The responses were as much as 4 times greater for drift and 2.3 times greater for shear force than the responses of fixed-base models.

• Structural Engineering and Mechanics
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• v.57 no.5
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• pp.785-808
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• 2016

An innovative Reduced Beam Section (RBS) connection, called Tubular Web RBS connection (TW-RBS), has been recently introduced and its performance has been numerically investigated in some earlier studies. The TW-RBS connection is a kind of accordion-web RBS connection in which part of the flat web of the beam is replaced by a steel tube at the expected region of the plastic hinge. This paper presents experimental results of three TW-RBS connections under cyclic loading. Obtained results indicated that TW-RBS reduces contribution of the beam web to the whole moment strength and creates a ductile fuse far from components of the beam-to-column connection. Besides, TW-RBS connection can increase story drift capacity up to 9% in the case of shallow beams which is much more than those stipulated by the current seismic codes. Based on the experimental results, the tubular web in the plastic hinge region improves lateral-torsional buckling stability of the beam such that only local buckling of the beam flange at the center of the reduced section was observed during the tests. In order to achieve a better understanding, behavior of all TW-RBS specimens are also numerically investigated and compared with those of experimental results.

• Steel and Composite Structures
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• v.17 no.5
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• pp.573-599
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• 2014

A new type of connection for steel-concrete composite bridges was developed by the Steel Structures Laboratory of Ecole Poytechinque $F{\acute{e}}d{\acute{e}}rale$ de Lausanne. Resistance to longitudinal shear is based on the development of shear stresses in the confined interfaces which form the connection. Confinement is provided by the reinforced concrete slab which encloses the connection and restrains the uplift (lateral separation) of the interfaces by developing normal stresses. The experimental investigation of the interfaces, under static and cyclic loading, enabled the development of the laws describing the structural behaviour of each interface. Those laws were presented by the authors in previous papers. The current paper focuses on the continuity of the research. It presents the experimental investigation on the new connection by means of push-out tests on specimens submitted to static and cyclic shear loading. Investigation revealed that the damage in the connection, due to cyclic loading, is expressed by the accumulation of a residual slip. A safe fatigue failure criterion is proposed for the connection which enabled the verification of the connection for the fatigue limit state with respect to the limit of fatigue. A numerical model is developed which takes into account the laws describing the interface behaviour and the analytical expressions for the confinement effect, the latter obtained by performing finite element analysis. This numerical model predicts the shear resistance of the connection and enables to assess its fatigue limit which is necessary for the fatigue design proposed.

• Current Optics and Photonics
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• v.6 no.6
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• pp.619-626
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• 2022

In this study, we develop a three-dimensional (3D) terahertz time-of-flight (THz-TOF) imaging technique with a large depth range, based on asynchronous optical sampling (ASOPS) methods. THz-TOF imaging with the ASOPS technique enables rapid scanning with a time-delay span of 10 ns. This means that a depth range of 1.5 m is possible in principle, whereas in practice it is limited by the focus depth determined by the optical geometry, such as the focal length of the scan lens. We characterize the spatial resolution of objects at different vertical positions with a focal length of 5 cm. The lateral resolution varies from 0.8-1.8 mm within the vertical range of 50 mm. We obtain THz-TOF images for samples with multiple reflection layers; the horizontal and vertical locations of the objects are successfully determined from the 2D cross-sectional images, or from reconstructed 3D images. For instance, we can identify metallic objects embedded in insulating enclosures having a vertical depth range greater than 30 mm. For feasible practical use, we employ the proposed technique to locate a metallic object within a thick chocolate bar, which is not accessible via conventional transmission geometry.